Effects of multiple stressors on aquatic macroinvertebrate communities in a mixed-land-use watershed

As urbanization continues, there is a need to identify and understand environmental stressors that impact stream condition in mixed-land-use watersheds. This study analyzed four years of aquatic macroinvertebrate community and environmental data collected from ten sites located at the mouths of first-order tributaries and along the main stem creek of a 23-km2, mixed-land-use watershed in central Appalachia. The main objectives were to 1) determine stream ecological integrity by analyzing stream macroinvertebrate taxonomic and trait-based composition and 2) assess which of 23 environmental variables explained significant variability in common community composition metrics (WVSCI, GLIMPSS, Biotic Index, % clingers, etc.). Results indicated that trait-based metrics had a stronger relationship with land use characteristics compared to taxonomic metrics. Regression analyses and ANOVAs revealed that, across all four years, increased total dissolved solids and conductivity were significant predictors of poor stream condition while increased pH and % agricultural land use (within the observed range of 5-26%) were significant predictors of improved stream condition. Multivariate analysis indicated that the most impaired sites had the greatest density of National Pollution Discharge Elimination System (NPDES) outlets. Overall, macroinvertebrates were more sensitive to in-stream water chemistry variables compared to physical habitat variables. These findings support the use of aquatic macroinvertebrates to detect environmental stressors in mixed-land-use watersheds. Results indicate that management approaches in West Run Watershed, WV, USA, should focus on storm water management and mitigating the effects of past mining to improve stream condition